Questions regarding password-based authentication and password management

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5
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2answers
2k views

How to check for empty passwords?

Looking at all the ssh-login attempts by script-kiddies I assume that there are messed up systems connected to the internet that have password-less accounts set up. But how to check a Linux/Unix ...
5
votes
2answers
485 views

Why is 8 numbers considered a “strong” password?

Just curious as to why 8 numbers are accepted as a password in linux (CentOS if it matters) and not 8 characters on a non-dictionary word. It's 10 vs 26 per digit after all. (52 counting CaSe ...
5
votes
1answer
190 views

Is it safe for my ssh user to be given passwordless sudo for `apt-get update` and `apt-get upgrade`?

I have an SSH standard user account on my personal server, and it has sudo access (via its password). I ssh in using a public key, so I don't have to type in the account password to log in. Is it ...
5
votes
1answer
810 views

What triggers this screen prompt “Screen used by <username> on host01.”?

Every now and then some key combination clears my working (Gnu) screen and brings up this message: Screen used by <username> on host01 Password: What key combination causes this and what does ...
5
votes
2answers
5k views

Graphically ask for password in a bash script and retain default sudo timeout setting

The sudo -A (SUDO_ASKPASS) option apparently causes sudo to lose the timeout (e.g., timestamp_timeout) setting. I want to use the sudo -A option but I want to retain the default timeout (e.g., 15 ...
5
votes
1answer
40k views

How to lock users after 5 unsuccessful login tries?

How to lock users after 5 unsuccessful login tries? I gathered a few distributions/versions to how to do it, but I can't test it. RHEL4: by adding the: auth required ...
5
votes
1answer
386 views

Automated ssh login with passphrase?

Logging onto a machine over ssh typically requires a password to be entered before access is granted. Alternatively, a key/certificate (without a passphrase) can be installed onto the remote machine ...
5
votes
2answers
426 views

Is it possible to change passwords temporarily?

I have a Linux system with several users. I don't know their passwords, nor do I want to know them. I have to do a batch copy of some of their directories over SSH, with their account and password. ...
5
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3answers
1k views

securely automating a script which requires a key to do its task

I have a script that downloads bank transactions to store in a database. To get these transactions requires a password for each account. The database is encrypted and requires a key to access it. All ...
5
votes
1answer
4k views

Changing password in multiple boxes using script

I'm working in a environment which has around 400 AIX boxes. I don't have root access and I'm a normal user. The environment has no LDAP kind of centralized mechanism for authentication so the ...
5
votes
1answer
4k views

Preventing `passwd` for asking for the local password

I have setup the sever to only use LDAP for authentication by using authconfig-tui. Everything works well but, when I run passwd, I get two prompts for a password: [beamin@rhel6-test-server1 ~]$ ...
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votes
4answers
2k views

automatic passwordless ssh at login/restart

I want to have passwordless ssh to persist even after after I restart or logoff and then login. Somehow I have to run ssh-agent and use command ssh-add at login. In a tutorial I read that I should add ...
5
votes
1answer
3k views

Samba passwords expiring in x days - how do we fix them to not expire

We use OpenLDAP and Samba v3. Recently some Samba-defined users (no accounts on the shared linux server) started being listed in logwatch as having their passwords come up to "will expire"...I ...
5
votes
2answers
2k views

Can KWallet manage my ssh passwords?

I need a way to store some SSH passwords. Note that these are login passwords which I need to pass to ssh; key authentication is unfortunately not an option. I'd like to be able to have KWallet fill ...
5
votes
1answer
569 views

how to verify if root password changed correctly

I have an OpsWare task, that changes root passwords on a massive number of servers, by replacing the root's password hash in /etc/shadow file. I need a script of some sort, which preferably runs ...
4
votes
3answers
808 views

Any disk encryption that locks itself for some time after a number of failed attempts?

Is there any way to have your disk/partition/file encrypted (in Linux or as a hardware encryption; no Windows here) in such way that it locks itself for say 10 minutes after say 3 failed unlock ...
4
votes
2answers
2k views

Sudo Su automated login

I want to automate the login process with sudo su. I have seen lot of questions on these, but none of them are working for me. Automate login with sudo and su Here's my what I tried so far echo ...
4
votes
3answers
4k views

SCP command with selected file and directories for download ask's for password for each new file or directory

On my Fedora 20 system I use scp a lot, and this is the second time I encounter this, when I run this command: scp -r -P PORT user@host:/home/user/something/{file1,folder1,folder2,folder3,folder4} ...
4
votes
3answers
860 views

Securely feeding a program with a password

After understanding the problem with using a password in the command line, I need to find a way of feeding a program with a password without it being a problem (without the password being recorded ...
4
votes
3answers
275 views

Automatic login via ssh (no GUI environment installed / no ssh-agent available)?

I have three systems, and I want to have them doing backups between them periodically. The two of them, have Debian Wheezy installed and the other one has Ubuntu 12.04 installed. Only the Ubuntu has a ...
4
votes
2answers
11k views

How to remove root password on Debian?

I'm running Debian in a virtual machine and for convenience I would like to remove the password on root (since it doesn't really matter what happens to this box). Internet hasn't been too helpful on ...
4
votes
2answers
193 views

Trying to crack a weak password using John

I have a computer from the 1990s. It has an (extent) EFS file-system which cannot be wrote to in linux, so i cannot reset the password manually. So i have to crack my password. For this I am trying to ...
4
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2answers
3k views

/etc/shadow date of last password change—UTC or local time?

man 5 shadow gives the following description of the third field in each line: The date of the last password change, expressed as the number of days since Jan 1, 1970. The value 0 has a ...
4
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2answers
228 views

Why rejection of password is much slower than acceptance of it? [duplicate]

In both my Linux and OSX machines when I type in the password to login, a correct password is accepted immediately. However, if I type a wrong password, checking process takes much longer. How is ...
4
votes
4answers
390 views

Login into a GNU/Linux distribution is taking too long

So, When I try to login with my username and password (in tty), and insert a wrong password, I need to wait around 5 seconds for the system to tell me that the password is wrong. Why the validating ...
4
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3answers
472 views

Something like pwgen-win for linux?

Is there some kind of pwd generator for Linux that has a nice GUI and options like this one for Windows? I know that there is pwgen, but as far as I know it does not support mouse/keyboard entropy and ...
4
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2answers
1k views

Why should you NEVER edit the /etc/shadow file directly?

In another answer here on UNIX & Linux Stack Exchange Michael D Parker wrote, in response to someone saying that doing so was "safe", that:Usually you should NEVER edit the /etc/shadow file ...
4
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4answers
52k views

Kali Linux: On install, designated root password cannot login - incorrect password

I found an old laptop lying around and I figured I would install Kali Linux on it to learn more about penetration testing and to try to break into my servers for practice and learning more about ...
4
votes
2answers
256 views

Determining the Password Status of a User

I have a debian box that I connect to via SSH. I have removed the password from the users root, and my personal account using the instructions here, and set up a public/private key pair so I can log ...
4
votes
1answer
18k views

How to set password for users in AIX using single line command?

Is there any way in which I can set the password for a newly created user account in AIX in a one line command? I don't want to give any prompt to the user. If there is a command, it should set the ...
4
votes
1answer
503 views

Encrypt word X to /etc/shadow encryption

I've changed my password to X and the shadow file has changed to: ahmad:$1$oYINSKjP$eCkCtJV/2dXerAD57WQPj/:15425:0:99999:7::: I see the encrypted X as $1$oYINSKjP$eCkCtJV/2dXerAD57WQPj/. How can I ...
4
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2answers
358 views

User created without a password behaves as if he had one

Inside one of my scripts, I created an user based on a directory arrangement on another machine. The thing is that this user, created without a password, behaves just as he had one : he has sudo ...
4
votes
2answers
426 views

Password protecting a system file? (e.g. /etc/resolv.conf)

I am trying to parental control myself by restricting web access via OpenDNS. The OpenDNS account password will be handed to someone trustworthy. Now, I want to put some restriction on the ...
4
votes
1answer
18k views

How to create a user with given password on SuSE from command line?

I need to create bunch of new users with given password. What I want is a script that I would pass the user name of new user and it will create/add the user and set its password. (the password is the ...
4
votes
3answers
2k views

scp: localhost password not accepted

I'm attempting to copy a public key to a remote server. I'm logged in locally as [localname] and the key resides locally at ~/.ssh/. I'm also ssh'd into [remote.com] as [remotename], and attempting to ...
4
votes
2answers
10k views

Avoid “Authentication token manipulation error” on password change

I'm implementing a security policy that will force the users to introduce stricter passwords when they change their own: The /etc/pam.d/passwd configuration file is: #%PAM-1.0 auth include ...
4
votes
3answers
293 views

Randomise or shred memory of an application

Is it possible to randomise or shred memory of a particular application just after its life ends, or better, whenever it deallocates some memory? A command-line utility like this would be perfect: ...
4
votes
1answer
90 views

How to achieve conditional PAM authentication?

I am currently using auth required pam_unix.so try_first_pass nullok auth optional pam_ssh.so use_first_pass (plus some other, probably irrelevant entries Arch Linux added by default), which means ...
4
votes
1answer
64 views

Is it possible to add a password to moving or copying specific files on Linux?

I have a directory setup very nicely(i.e organized with READMEs and easy navigation etc.). I would like people to be able to access the files in this directory maybe even copy them to their own ...
4
votes
1answer
188 views

Change the root password of a Linux image

I'm building a jessie build of Debian. Passwords are saved in /etc/shadow in the build tree, but they are salted obviously so I cannot change it just by editing the file. If this was my installed ...
4
votes
2answers
189 views

SSH password requested when in Tmux

When I connect to my remote machine I do authenticate using a rsa key (I think is rsa, don't remember). If I do ssh from a regular shell I get logged on the machine without a password. However if I ...
4
votes
1answer
357 views

Export passwords from the `pass` password manager

I've been using the pass password manager for a year or so now, and it's awesome, but sometimes I like to test other password managers and then I need my passwords back. So far I've just been adding ...
4
votes
1answer
120 views

Self-contained password manager with CLI [closed]

I'm looking for a password manager that has the following properties: The manager is entirely self-contained. I take and install a directory on a thumbdrive and execute from that drive. It should ...
4
votes
1answer
3k views

Debian Log In Failure With Correct Password

So I have a Debian distro at home (considering getting ubuntu), and I can't login. When I use the correct password is does this thing where it makes it look like it's going to login, and then it ...
4
votes
1answer
1k views

Why ssh-copy-id prompts for the local user password three times?

Noticed from my previous question that when trying to copy an SSH public key to a remote host via ssh-copy-id, I am prompted for the local user password three times: ssh-copy-id myuser@myserver ...
4
votes
2answers
2k views

Two-step remote ssh without password

I'm looking to ssh from my localhost to a remote server, and from there to a remote computer. I currently have it set up so that the remote computer and remote server have passwordless ssh-ing set up ...
4
votes
2answers
38 views

Understand the PasswordAuthentication in sshd configuration

I have an OpenSSH server which supports only password authentication: [martin@ ~]$ ssh -v 10.10.1.183 -l root OpenSSH_5.2p1 FreeBSD-20090522, OpenSSL 0.9.8k 25 Mar 2009 debug1: Reading configuration ...
4
votes
2answers
148 views

how to prevent a buffer from swap

this question is specific to Unix and Linux. but it is programming and security, too. my program will get a clear password or decryption key by one of a few ways (decrypting a password file, asking ...
4
votes
2answers
364 views

How can I check GMail messages with prompt for password from a script?

I'm using zsh on Ubuntu 14.04 over SSH using Putty and I'm setting up the key bindings for my keyboard. Because zsh doesn't seem to make use of my function keys I thought I'd setup scripts to do ...
4
votes
2answers
16k views

Change Password of a user in /etc/shadow

I would like to change the password of a user in the /etc/shadow. I can't use password changing programs like passwd. It must be done by editing the /etc/shadow. The /etc/shadow is on a mounted hard ...